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Academic research trends involving public health education may reflect a certain degree of talent construction status. This study systematically reviews the data for published literature on graduate public health education, aiming to provide evidence for the optimization of public health postgraduate training mechanisms in China. Keyword cooccurrence analysis was performed based on high-frequency keywords. From 1992 to 2008, the annual number of publications in this field was relatively low in China, averaging fewer than 5 articles. The number of publications showed a steep increase after 2009. The publications were mostly from single research institutions, including comprehensive universities and military medical universities, concentrated in Beijing and Shanghai. The high-frequency keywords were public health and preventive medicine, postgraduate training, professional degree, MPH, curriculum, and teaching reform. Hotspots consisted of practical teaching research, training, educational reform and comparative education research. Research on public health postgraduate education has not reached scale and has insufficient support. Moreover, many problems in graduate public health education still cannot be solved by existing studies: authentic and practical learning, a unified approach to cultivate graduate students, organizational change of graduate public health education, and international cooperation and public health education. more...

Natural gas hydrate solid fluidization mining technology is a new hydrate mining technology, but due to the lack of combined nozzle design theory and basis, the crushing efficiency of mining tools is low. To solve this problem, the characteristics of the combined jet flow fields of nozzles with diameters from 1 mm to 4 mm and combination angles from 10° to 20° were studied in this paper by means of experiments and simulations. The results show that the maximum velocity at the merging point increases negatively linearly with increases in the combination angle and positively linearly with increase in the nozzle diameter. The position of the merging point changes little with the nozzle diameter and increases exponentially with increases in the combination angle. The effective crushing lengths of nozzles with different diameters all turn (increase first and then decrease) when the combination angle is 12.5°. The optimal combination angle for nozzles with diameter less than 4.5 mm is 12.5°, and 15° is for nozzles with diameter more than 4.5 mm. This study reveals the flow field variation mechanism for the combined nozzle and provides guidance for the design of the combined nozzles of gas hydrate combined nozzles. [ABSTRACT FROM AUTHOR] more...

Rail braces are important components for reinforcing tracks in railway curves and steep slope sections. Field surveys have identified several issues with existing rail brace structures, such as uneven local stiffness, poor adjustability, and multiple types. The uneven stiffness in existing structures causes some fasteners to fail in providing adequate lateral support, leading to significant impacts on tracks and resulting in poor track conditions. Furthermore, poor adjustability leads to gaps between the rail braces and the rail web, causing improper contact. Over time, this can damage both the sleepers and the rails, complicating track maintenance and operations. To meet the demands of heavy-load railways, mixed passenger-freight lines, and other railway applications, a series of elastic rail braces for 50 kg/ m, 60 kg/ m, and 75 kg/ m specialized rails were developed. These braces featured a one-piece design that ensured full contact between the rail braces and the web, increasing the contact area and improving lateral resistance. Elastic rubber or polyurethane materials were embedded (vulcanized) into the sides of the rail brace, preventing hard contact with the rail. The design allowed for slight displacement, maintaining elasticity and reducing the abrasion and damage caused by rail braces pressing against the web. A solid model of elastic rail brace was established using the finite element method to theoretically analyze its stress distribution and determine reasonable technical parameters. In addition, testing methods and technical requirements for assembling the elastic rail braces were developed. Indoor comparative tests were carried out under identical conditions with the type II elastic fastener used in China's railway. The results showed that all indicators met expectations, demonstrating the design's safety and reliability. To further validate its practical applications, field trials were conducted on a small-radius curved track with a radius of 400 m. Observation data indicated that the elastic rail brace effectively resisted the abnormal lateral load on the rails, with minimal track gauge variation rate. The design meets the required standards, ensuring safe train operations, and has significant potential for widespread applications. [ABSTRACT FROM AUTHOR] more...

A reconfigurable transducer interface circuit that combines the communication and signal conditioning necessary to link a variety of sensors and actuators to a microsystem controller is reported. The adaptive readout circuitry supports high-resolution signal acquisition from capacitive, resistive, voltage and current mode sensors with programmable control of gain and offset to match sensor range and sensitivity. The chip accommodates sensor self test and self calibration and supports several power management schemes. It provides digital and analog outputs to control actuators and a standard interface to peripheral components. The 2.2 x 2.2 mm CMOS chip was fabricated in 0.5-[micro]m, 3-metal, 2-poly process, dissipates ~ 50 [micro]W at 3.3 V in a typical multisensor application utilizing periodic sleep mode, and can read out a wide range of sensors with high sensitivity. A prototype microsystem with a microcontroller and MEMS pressure, humidity, and temperature sensors has been implemented to characterize interface chip performance. Index Terms--Adaptive circuits, microsystem, sensor interface. more...

This paper introduces and analyzes a flux reversal machine (FRM) configuration for low-speed (below 150 r/min) servo drives. The FRM configuration includes stator poles with three-phase concentrated coils and 2np alternate polarity permanents magnets per stator pole and a salient multiple-pole passive rotor. In-depth finite-element method analysis shows high torque density and less than 3% torque pulsation (through adequate rotor skewing) with sinusoidal three-phase vector control. Index Terms--Finite-element method (FEM) analysis, flux reversal machine (FRM), pole-permanent magnet (PM) configuration. more...